Arterial blockages caused by the build up of plaque in the arteries of a patient can have grave consequences. Specifically, the build up of plaque in arteries can reduce and eventually block blood flow through the affected vessel. When blood flow is reduced in a coronary artery, the heart muscle becomes deprived of oxygen, and the patient is prone to suffer angina. In severe cases of coronary artery blockage, the patient can suffer a heart attack.
Many modern surgical techniques have been developed to alleviate the stenoses that are formed when plaque builds up in a patient's arteries. For example, a large number of balloon angioplasty devices exist for relieving arterial stenoses by compression of the stenosis. In several respects, balloon angioplasty devices afford numerous advantages over alternative methods. Foremost among these advantages is that open heart bypass surgery can often be avoided by using angioplasty surgical techniques to relieve stenoses in the arteries that supply blood to the heart. For obvious reasons, it is preferable to avoid open heart surgery when possible because such surgery, as is well known, is invasive and typically requires a significant post-operative recovery time. Accordingly, it is preferable to use relatively simpler angioplasty surgical procedures when such procedures are feasible. Importantly, angioplasty procedures are efficacious in the peripheral arteries as well as in the arteries that supply blood to the heart.
In angioplasty surgery, the balloon of a balloon catheter is initially attached to a catheter tube in a deflated configuration, with the catheter tube connecting a fluid source in fluid communication with the balloon. The balloon is then positioned at the desired location in the affected artery by advancing the catheter through the artery until the balloon is positioned across a stenosis that is to be treated. Once the balloon has been properly positioned, fluid is infused into the balloon. As the balloon expands, it dilates the lumen of the artery and compresses the plaque which may then break up or flatten out against the arterial wall. The balloon is then deflated and, once in its deflated configuration, it is either withdrawn from the artery or placed across another stenosis, to restore normal blood flow through the artery.
A particular problem associated with an angioplasty procedure exists during the deflation stage of the balloon, prior to its removal from the artery. Specifically, it is desirable that the balloon be deflated as tightly as practicable to facilitate its removal from the arterial passageways. In any case, the key to removing the balloon catheter with ease is having the balloon collapse evenly and compactly during balloon deflation. Once deflated, the balloon catheter must often travel through the tortuous vasculature of the patient and it is, therefore, important for the balloon to deflate uniformly into a predictable configuration. If the balloon fails to deflate in a uniform manner, an irregular bulge in the balloon may cause difficulties in withdrawing the balloon catheter from the artery.
In addition to the conventional, percutaneous, transluminal coronary angioplasty (PTCA) and percutaneous, transluminal angioplasty (PTA) procedure described above, cutting balloons are currently viewed by many as the next generation treatment option for the revascularization of both coronary and peripheral vessels. The cutting balloon mechanism is unique in that the balloon pressure is distributed over one or more blades (i.e. microtomes). The blade(s) function as stress concentrators and cut initiators in PTCA and PTA procedures. Consequently, PTCA and PTA procedures have been proven to minimize vessel recoil, lessen vessel injury and lower the rate of restenosis, as compared to conventional PTCA and PTA procedures. However, the cutting blades used in cutting balloons are extremely sharp (e.g. three to five times sharper than a conventional scalpel), and in the absence of special precautions, have the potential to inadvertently incise non-target tissue during in vivo movement of the cutting balloon to and from a stenosis.
In light of the above, it is an object of the present invention to provide a device that is useful for folding a balloon predictably and compactly onto a catheter tube during balloon deflation to facilitate in vivo movement of the balloon catheter. Another object of the present invention is to provide a device for maintaining the balloon tightly wrapped on a balloon catheter when the balloon is in a deflated configuration. It is yet another object of the present invention to provide a device that is useful for folding a cutting balloon during balloon deflation into a configuration in which the blades become nestled within a pair of adjacent balloon pleats to prevent the blades from inadvertently incising tissue during an in vivo movement of the balloon catheter. Yet another object of the present invention is to provide a device which is relatively simple to manufacture, easy to use, and comparatively cost effective.